This invention relates to pneumatic tires, and more particularly to the venting of the bead area of trapped air under pressure to prevent ply separation and destruction of the tire.
U.S. Pat. No. 3,448,520 issued jointly to this applicant and others, explains the need for venting the bead area of pneumatic tires and describes an awl-type piercing tool for forming air vent opening in the tire. This procedure is quite satisfactory for small tires of the passenger car type and others provided with up to three bead clusters, but is not completely satisfactory for the much larger tires utilized by heavy, off-road vehicles and large aircraft and containing up to five or more bead clusters.
The aforementioned patent also illustrates a porous member extending from the bead area to the outer side of the tire for allowing air under pressure to pass through the porous member and escape to the atmosphere. However, the patent discloses that the porous member is installed in the tire during its manufacture, before final curing of the rubber. This adds significantly to the time and cost of tire production. Furthermore, it provides no means by which to overcome the problem in tires already manufactured.